The interactions of lipoproteins and artery wall cells are being studied in this Specialized Center of Research on Atherosclerosis. The grant supports the coordinated efforts of eight tenured faculty members, two assistant professors and a number of research associates from Biochemistry, Medicine and Pathology who are investigating the factors controlling the pathogenesis and the regression of atherosclerosis. The program includes investigation of the structure, molecular interactions, synthesis, secretion, degradation and molecular metabolism of lipoproteins. The interactions of various serum lipoprotein fractions and components with the artery wall and with the multifunctional medial mesenchymal cells are being studied both in vivo and in vitro, especially their effects on cell proliferation, fiber protein synthesis, cell lipid metabolism, lipid accumulation as well as cell degeneration and necrosis. Immunohistochemical approaches and ultrastructural observations, sometimes in combination, are being used in these studies. Atherosclerosis reversal studies in intact animals, myocardial infarction in atherosclerotic and non- atherosclerotic monkeys and the effects of lipoproteins and artery wall components on coagulation and fibrinolysis are included in the Center activites. Exploratory work is beginning on the lipoproteins and the cells of patients with severe atherosclerosis and ischemic myocardial disease who have no evidence for any of the lipoprotein, metabolic or artery wall abnormalities. It is hoped that these studies will help identify new factors which contribute to ischemic heart disease in these patients. Bibliographic references: Fischer-Dzoga, K., Jones, R.M., Vesselinovitch, D. and Wissler, R.W. Increased mitotic activity in primary cultures of aortic medial smooth muscle cells after exposure to hyperlipemic serum. In: Atherosclerosis III: Proc. III International Symposium on Atherosclerosis, West Berlin. Schlettler, G. and Weizel, A. (eds.), p. 193-195. Springer-Verlag, Berlin, 1974. Wissler, R.W. Atherosclerosis - Its pathogenesis in perspective. In: Comparative Pathology of the Heart, Adv. Cardiol., Vol. 13, pp. 10-31, Karger/Basel, 1974.